4 CYRTIDAE OF NORTH AMERICA 



and the genus Panops. Wiedemann made two divisions: those 

 with, and those without ocelH. 



Erichson's "Monograph of the Henopidae" was pubhshed in 

 the " Entomographien" in 1840. A very good synopsis of the 

 family is given in this paper. Erichson made three subdivisions : 

 the first division with a long thin Bomhylius-Vike proboscis, car- 

 ried pointed back under the body when at rest and not porrect; 

 in the second division, those species having only a stump of a 

 proboscis were included. The third division contained only 

 those having absolutely no mouth-parts, a membrane closing the 

 mouth opening. The genus Ogcodes was the only member of 

 this last group. 



Erichson noted the importance of the antennae in classifica- 

 tion, their structure and the position occupied on the head. He 

 stated that the eyes are most broadly separated in Pialea, which 

 has two ocelli; Astomella has none. The structure of the an- 

 tennae and their position on the head formed the basis of the 

 separation of the different forms, thirteen genera being included 

 in the table: Panops, Lasia, Cyrtus, Psilodera, Thyllis, Philopota, 

 Ocnaea, Astomella, Pialea, Pterodontia, Acrocera, Terphis and 

 Ogcodes. In these genera forty-seven species were known at 

 that time. Dr. Erichson, in discussing the systematic relation 

 of the family, stated that he thought the Cyrtidae (Henopidae 

 as he called them) might be limited on the one side by the 

 Syrphidae, and on the other by Conops, Myopa and perhaps 

 Oestrus. 



In 1851, Walker gave some notes on the family in "British 

 Diptera," adopting the name Acroceridae. Only two genera were 

 known from England, Acrocera and Henops, and both were 

 briefly described. In 1854, Walker published a short revision of 

 the family, with a table of eighteen genera, Pteropexus, Exetaxis, 

 Eriosoma, Physegaster and Sphaerogaster having been added since 

 Erichson's "Monograph." Walker gave only a short Latin de- 

 scription of the species and a description of the wing venation of 

 each genus in English. 



In 1856, Gerstaecker made a valuable contribution to the knowl- 

 edge of the family in his paper, "Beitrag zur Konntnis der Hen- 

 opier" (42). In 1862, Schiner gave a short synopsis of the family 



